How to use the load cell correctly

With the change of time, the rapid development of electronic weighing instruments in our country, in terms of large-scale weighing instruments, heavy-duty long-size truck scales are generally put into use, and some new problems have appeared before us. In particular, the change in length of the steel structure load carrier affected by thermal expansion and contraction will directly prevent the load cell from transmitting the force value vertically; second, it will affect the gap size of the limit device, or even die. In order to ensure the accuracy of the measurement performance, what structure should be selected for the load cell becomes a question when customers choose. At present, the weighing sensors used on large scale weighing instruments at home and abroad roughly include: column type load cell, bridge type load cell, double shear beam lifting ring load cell, axisymmetric torsion ring type load cell, spoke type load cell, etc. .

The characteristics of several load cells

1. Column type load cell

Advantages: compact structure, strong overload capacity, high natural frequency, fast dynamic response, convenient installation, and low manufacturing cost.

Disadvantages: poor resistance to lateral and eccentric load (dual diaphragm structure is better), inherent linearity is poor, and the load cell is not easy to fix and rotate.

2. Bridge type load cell

Advantages: insensitive to loading point changes, good anti-eccentric load performance, good inherent linearity, convenient installation, fixed and non-rotating load cell, low manufacturing cost.

Disadvantages: The center of gravity is high, the overload capacity is poor, and it is difficult for a large-scale load cell to reach a high accuracy level.

3. Double shear beam lifting ring load cell

Advantages: good anti-eccentric load performance, and the load cell is fixed and does not rotate.

Disadvantages: complex structure, troublesome installation, high manufacturing cost, poor overload capacity, and large space occupation. Such products are not suitable for manufacturing large-scale structures.

4. Axisymmetric torsion ring type load cell

Advantages: compact structure, small size, low height, light weight, good inherent linearity, high accuracy, no deformation or small deformation of the bottom ring after loading, almost no hysteresis, insensitive to eccentric load and side load, input and output impedance Large, the load cell is fixed and does not rotate.

Disadvantages: installation is slightly more complicated, and the manufacturing cost of accessories is higher.

5. Spoke type load cell

Advantages: strong anti-eccentric load and lateral load capacity, strong overload capacity, not affected by the loading point and support boundary, uniform stress release, good linearity, and the load cell is fixed and does not rotate.

Disadvantages: difficult mechanical processing, high manufacturing cost, large inherent lag and difficult to control.

It can be clearly seen from the structure of the above five types of load cells that only the elastic body of the column type load cell moves with the shaking of the carrier during use, that is, the vertical load cell column during installation. The length of the thermal expansion and contraction changes, and the column of the load cell is offset, which causes the force to produce a component, so that the load cell has a weighing error. The other four types of load cells are fixed because of the elastic body. When thermal expansion and contraction affect the length of the carrier and the sway of the carrier, only the indenter is offset, and the elastic body that transmits the force will not follow. The change of the load carrier moves, so that the force on the load cell can be transmitted vertically, and the impact on the weighing performance of the truck scale is relatively small; at the same time, because the elastic body does not shake with the load carrier, the elastic body does not rotate. , The cable will not wrap around the elastomer.

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